The invention concerns a simplified approach to removal of the core from a gas turbine engine.
FIG. 1 is a schematic of a twin spool gas turbine engine found in the prior art. Incoming air 1 is compressed by a booster 2, and then delivered to a high-pressure compressor 3, which further compresses the air and delivers the compressed air to a combustor 6. Fuel is added to the combustor 6 and ignited, producing a high-velocity gas stream 9.
The gas stream 9 is delivered to a high-pressure turbine 12, which extracts energy to drive the high-pressure compressor 3, through high-speed shaft 15. The gas stream 9 is then delivered to a low-pressure turbine 18, which extracts energy to drive the booster, through low-speed shaft 21, and to drive a fan 24. The fan produces thrust. indicated by arrow 27. Some additional thrust 28 is produced by the gas stream exiting the low-pressure turbine 18.
Bearings 30 support the high-speed shaft 15 on the low-speed shaft 21. Bearings 33 support the latter low-speed shaft 21 on stationary structures, not shown.
Maintenance and repairs are required on the engine, some of which require removal of the core of the engine. The core, indicated by dashed box 29, includes the high-pressure compressor 3, the high-pressure turbine 12, the shaft 15, and a casing 31 which contains these three elements. Typically, in the prior art, major disassembly of the engine is required for removal of the core 29.
The inventor has developed a strategy for removal of the core 29 which avoids the need for major disassembly of the engine.
In one form of the invention, a nut which locks a shaft in place in a gas turbine engine is equipped with a second thread. The second thread is used to engage another thread provided nearby, when the nut is removed. Thus, when the nut is removed from the shaft, it can be threaded onto the second thread, and need not be removed from the engine. The latter type of removal ordinarily requires removal of extensive amounts of additional components.